Camshaft phasers are used in combustion engines to vary the valve timing of the combustion chamber valves to be able to variably construct the phase relationship between the crankshaft and camshaft within a defined angular range between a maximum advanced and a maximum retarded position. Consumption and emissions are reduced by adapting the valve timing to the actual load. For this purpose, camshaft phasers are integrated in a drive train via which a torque is transmitted from the crankshaft to the camshaft. This drive train can be realized as a belt, chain or gear drive, for example.
In the case of a hydraulic camshaft phaser, the output element and the drive element form one or a plurality of pairs of pressure chambers which act in mutual opposition and can be pressurized by oil. In this case, the drive element and the output element are coaxially configured. A relative movement between the drive element and the output element is generated in response to the filling and emptying of individual pressure chambers. The spring acting rotationally between the drive element and the output element impels the drive element in an advantageous direction relative to the output element. This advantageous direction can be co-rotational or counter-rotational to the direction of rotation.
One common type of hydraulic camshaft phaser is the vane-type adjuster. Vane-type adjusters have a stator, a rotor and a drive element. The rotor is mostly nonrotatably connected to the camshaft and forms the output element. The stator and the drive element are likewise nonrotatably interconnected and are also optionally formed in one piece. The rotor is disposed coaxially to and within the stator. Via the radially extending vanes thereof, the rotor and stator form oil chambers which act in mutual opposition, can be pressurized by oil, and which make possible a relative movement between the stator and rotor. In addition, the vane-type adjusters have various sealing covers. The stator, drive element and sealing cover are secured by a plurality of screw connections.
Another known type of hydraulic camshaft phaser is the axial piston adjuster. In this case, oil pressure axially displaces a slide element which, via helical toothing, generates a relative rotation between a drive element and an output element.
Another type of camshaft phaser is the electromechanical camshaft phaser which has a three-shaft gear system (for example, a planetary gear system). One of the shafts forms the drive element, and a second shaft, the output element. Rotational energy can be supplied via the third shaft to the system by an actuator, for example, an electromotor or a brake, or removed therefrom. A spring can likewise be configured to support or return the drive element and the output element during the relative rotation thereof.
The German Patent Application DE 10 2007 039 282 A1 describes a vane-type adjuster having a belt pulley for driving the camshaft phaser, and having a plastic part, a fluid-tight space being formed by the connection of the two components. The connection is realized by latching tabs in circumferential elongated holes and provides a form-locking in the axial direction. However, since the undercuts of the latching tabs can become loose in operation, wedge elements are introduced that are intended to prevent the latching tabs from springing back. These wedge elements safeguard the form-locking engagement and ensure that it can no longer become loose during operation.